Body of Lies: Debunking the BMI

By Ashley-Michelle Papon

It’s that time of year again: swimming pools are opening, students are jogging, and if you’re a mom, you’re probably getting fat. According to a new study released in Pediatrics, the official journal of the American Academy of Pediatrics, young mothers are more likely to make poor dietary decisions, less likely to exercise, and have a higher Body Mass Index, most commonly known as the BMI.

The United States has a firm history of economically punishing teenage mothers by denying them access to better resources including healthier food. Still, the most troubling pretext of the article has little to do with the gender disparity or economics skewed to keep the poor poor, but the implication that the BMI of young mothers is an indication of just how unhealthy they are.

Though the BMI has long been touted by medical and athletic communities as the greatest tool of measurement to determine someone’s health, stricter academic scrutiny and authentic scientific study is finding that the BMI as a gauge of health is flawed. Contrary to what you have probably heard several times over, the BMI is not an accurate indicator of how “overweight” you are. And it’s certainly not a viable indicator of your health.

In July of 2009, Keith Devlin of the National Public Radio shared with the world 10 reasons why the BMI is bogus. Urging listeners and readers to take the BMI—and their next meal—with a grain of salt, he patiently explained that, at its core, the BMI was a nonsensical, physiologically inaccurate formula created by mathematician Lambert Adolphe Jacques Quetelet in the early 19th century. Quetelet’s method to create a measurement was calculated by dividing one’s weight in kilograms by the square of their height in meters.

Although it may seem scientifically sound at first blush, the methodology creates no distinction between the weight of muscle versus the weight of fat, despite the fact that fat takes up roughly four times the space of muscle. In other words, there can be quite a difference in your weight and size based on your body type. By failing to evaluate the two body features separately, the BMI delivers faulty results that make being classified as overweight a virtual certainty. And though BMI has some level of success with whole groups of people, its use to determine how healthy one adult can be is questionable at best.

But the biggest weakness with BMI would have to be how it attempts to lock people into rigidly defined categories for underweight, ideal, overweight, and obese. The scale, ranging from 1 to 100, becomes overweight at 25 and obese at 30; it is transfixed in such a way to suggest that when individuals reach 25 or above, they’ve crossed into the territory of being unhealthy. This conclusion begs the question of what unhealthy actually looks like. By relying solely on the BMI for the numeric answer to this question, the aesthetics often don’t bear out to compliment the BMI’s ranking.

And although people think they can eye it the way they can parallel parking, a true visual assessment of one’s physique isn’t something that can be winged. In one of her earliest criticisms of the BMI, blogger Kate Harding launched a photo project showcasing woman with their height, weight, BMI, and a commentary about the accuracy of the BMI’s rating. One volunteer, Laurie, 5’0 and 130 pounds, carries a BMI of 25.4 percent. According to the BMI, Laurie is “overweight,” despite being a size 4. For emphasis, Harding showcases several curvier women, warning viewers not to get too attached because the BMI’s validation that they’re unhealthy suggests they will drop dead of heart attacks and diabetes soon.

Harding’s point was drastic, but the photographs of everyday women unable to meet these unrealistic body standards hammer home the damage done by the promotion of outdated rubrics employed to shame our bodies. What was pioneered in the interest of helping advance medicine has become a modern tool of extremely organized bio-power. The cultural and social obsession with weight management for women has always gone hand-in-hand with the desire to render them less powerful. In a very real sense, the physical reduction of their size is a stripping down of their agency. Since Kevin Smith gave up directing movies and became a factivist following his ejection from a Southwest flight for being “too fat,” this schism has widened to keep persons of size from inheriting power, often out of concern for their health.

Except that that brings us back, full circle, to why the BMI is completely bogus. The BMI is billed in a way that if someone has a BMI that places them in the “overweight” range, they are immediately considered unhealthy. Yet new research is finding that heavier people actually have more protection against a number of illnesses and chronic conditions, from kidney failure to infectious diseases and lung issues.

Despite this, it’s not going to stop the diet industry from using the BMI to keep pushing their products. Social attitudes notwithstanding, sources like the International Obesity Task Force and the American Obesity Association are treated as completely legitimate entities when they use the BMI to explain how we, as a society, are doomed because of our size. Despite authoring the majority of the World Health Organization’s obesity reports, both organizations are primarily funded by pharmaceutical and weight loss companies. Is it any wonder that these folks (and others associated with them) have been aggressively campaigning to have obesity classified as a disease? As Paul McAleer over at BigFatFacts concludes, “The ‘obesity epidemic’ is worth billions to the pharmaceutical, diet, weight loss, media, and government agencies fueling it.”

This should leave every person asking themselves: do I want to keep banking my health on a tool designed to tell me my body is flawed so that the companies employing that tool can continue creating a billion-dollar industry?

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13 thoughts on “Body of Lies: Debunking the BMI

  1. I agree that the BMI is just not that accurate. I was very overweight and so far have lost approx. 65 pounds, and do need to lose more. My issue with the BMI is that it does not take into account a person’s body frame and whether they are big boned, fine boned, or average. I am a large framed woman with big bones. When I lie down, my ribs stick out, yet I am still in the catagory of “obese” according to the BMI!

  2. Thanks for all the great feedback, folks. I appreciate knowing the article is being read, digested, and discussed.

    However, I want to respond to some points raised. The first being that the BMI is “just a screening tool.” Even if I agreed that the BMI is simply a screening tool with limited usefulness, I would be flying in the face of everything that has been culturally and in most cases medically accepted as an accurate indicator of your overall health.

    As if life somehow wanted to make this point for me, the same day this article came out, I had a doctor’s appointment. While I was stuck waiting to be seen, my eyes immediately fell to the chart on the wall–sure enough, it was a BMI chart, peppered with fliers for hospital-sponsored weight clinics and scary-looking posters of how being overweight would ruin your life and kill you. The poster mentioned specifically that being overweight was defined by your BMI. I snapped a photo of it with my iPhone and uploaded it to my Facebook wall, mostly to respond to my friend who disputed any medical professional or organization would actually tout the BMI’s findings.

    This is after years of gym memberships and personal training sessions where the weight loss goal was not determined by my idea of the ideal weight, but what the BMI standard determined was my ideal weight. And years of being told by doctors of various degree-holding that lowering my weight to the BMI-appropriate range would solve all of my various medical ailments, from pollen allergies to the torn cartilage in my knee. The same cartilage which was torn while I was very thin, playing volleyball, softball, and competitively dancing.

    Basically, if the BMI is simply a tool to establish a baseline, it’s about as functional as trying to use a spaghetti noodle as a leveler for hanging shelves.

  3. When I was anorexic and my ribs were sticking out, my BMI was still in the “normal” range (which in turn induced me to eat even less). The ridiculousness of this touted dietary tool as a supposed “one-size-fits-all” depiction of weight is only topped by the continuance of doctors and other authorities to use it. Great article, thanks.

  4. The BMI is just a screening tool… If everything is ok. then that’s that.

    Except, of course, when this is not the case. I’ve had providers advise me — based on BMI alone — to lose weight:

    — to manage endometriosis
    — to improve pelvic floor dysfunction
    — to reduce allergy symptoms
    — to heal a broken foot
    — at a new patient annual exam when presenting with no acute health complaints

    While my experiences aren’t universal, they’re also not a rarity.

    Absolutely, it makes sense to look at a patient’s history and lifestyle when making recommendations for overall health. But: 1) it makes sense to do that regardless of BMI; 2) it’s sometimes ignored in favor of BMI, best practice notwithstanding.

  5. Both BMI and body fat are very poor predictors of health. 95% of those scare studies are sponsored by Pharma. They have ridiculous tricks like including all the dangerous diet practices in with obesity. It is high time we stop allowing ourselves to be manipulated. Years ago, many fat people lived long, healthy, productive lives. Today the medical industry kills them, then blames the victim!
    “I have never had a problem with my weight that wasn’t caused by other people!”

  6. I am overweight. I know it, and I am actively doing something to reduce my weight to reduce the implications to my health. But my BMI puts me as obese. I don’t believe that it’s accurate, but it’s done a wonderful job at making me feel awful about myself for months. This was exactly what I needed to read.

  7. I’ve always known the BMI was bogus (according to it, I should weigh 130. Anything under 155 and I start to look skeletal), but was never able to put into words why that was. This post is brilliant.

  8. The BMI is just a screening tool. If the patient is at a high or low BMI, then we look at their history and physical exam and exercise and diet history (and menstrual history if relevant). And we might draw some blood work to check the health of this person (lipids, rule out thyroid problems). If everything is ok. then that’s that. But if we discover they are sedentary or exercising too little or too much, then we advise them to get healthier. If we find high blood pressure, acanthosis nigricans, etc. then we encourage weight loss and activity.

    So I disagree with the author in calling the use of the BMI as a “body of lies.” The study simply stated a fact they found in their research- young mothers have higher BMIs. They used BMI b/c that is probably the data that they had. It would have been more costly to do body fat and blood tests and they didn’t have the budget or didn’t want to subject people to invasive tests. Research is limited by budget, etc.

  9. In the absence of measuring body fat I would agree that BMI needs some work. However statistics also show that in non exercising persons the higher the BMI the more the more health care that person needs. Someone with a BMI in the “normal range” uses about $3000 per year on healthcare (ave) while those above 40 BMI uses above $8000 per year.

    Bottom line, measure BMI in addition to body fat -and waist circumference – to get a more broad picture of health risk status. Something else to consider, overweight people who exercise -regardless of weight loss – still outlive skinny people who do not exercise…


  10. Great article! BMI does not accurately measure health. I have always been “underweight.” At a BMI of 17.4, that is the highest it has ever been. I have always consumed more calories than my peers. I tried and tried for years to put on weight so I wouldn’t look s “puny” but my body simply wasn’t having it. I am a little more weighty than I was in high school mainly because I have gained muscle which weighs more than fat. If I didn’t gain the muscle, I’m pretty sure I would still be 85 lbs instead of 95, what I am now.

    I’ve been to many doctors throughout my life. Some of them said I could stand to gain a few, but most of them understood that it would probably require me eating an unhealthy amount of food to do so, so they said that since I already eat plentiful and keep active that I need not worry about it. They say that being underweight is worse than being overweight but I don’t think so. I don’t think one is worse than the other. My health has never suffered from having a low BMI. This is just how I was genetically meant to be.

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